Manufacture of starch



Jan. 11, 1938. A. H. KELLING 2,105,217

' MANUFACTURE 0F sTARcH original Filed June 12, 1933 2 sheets-sheet 1 Gem Germs @al 1 llzatenlteii Jain1 11;, 1938 I MANUFACTURE OF STARCH Alfred H. Kelling, Oak Park, Ill., assigner to linternational Patents Development Company, Wilmington, Del., a corporation of Delaware originan application June 12, 1933, serial No.

,1 5 Claims.

This invention relates to the manufacture ol starch from corn by the wet method; and particularly to a process in which all, or substantially all, 'of the process Waters (except the steep eration, as has been customary for many years.

Divided and this application June 4, 1936, Serial No. 83,536

(ci. 12v-csr Starch tables require a great deal oiloor space and are expensive to maintain in repair, besides requiring constant attention in respect particularly to the maintenance of proper flow of the 5 water and the .water absorbed in the discharged mill starch over the tables, upon which the ade- 5 solids) `are returned to the process for re-use, for quacy of the separation depends. Of late years the purpose of saving the solids, soluble and init has been customary to return to the process soluble, therein, and preventing the' pollution of for re-use all process waters, or at least a very streams which results from discharging process large proportion `of the process' waters, for the l@ waters from the factory. i purpose of saving soluble substances contained l0 In the manufacture of starch from corn it has therein and preventing streaml pollution. Ap-

been customary to steep the c orn and withdraw plication Serial No. 675,412, discloses several the steep water. to evaporators for recovery of methods according to which centrifugal machines the corn solubles contained therein. The steeped are. substituted for starch tables with such ar- 15 corn is then comminuted and subjected to separangements-of the instrumentalities for carrying 16 rating operations in Water for removal of the out the process that, in the iirst place, all process germs, hulls and fiber. The` usual method has waters may be re-absorbed in the system; that been to break up 'the corn coarsely, separate the in the second place, the process Water which by germs by notation and wash the germs to rethe nature of the process contains the largest move starch and gluten; then grind the residue quantity of soluble substances and the Water 20 of `the corn material as finely as possible, and which has necessarily been longest in the process, subject the ground material to what is known as and for these reasons will be the most highly ina coarse slop separating or washing operation in fected with micro-organisms, to-wlt, the water which starch and gluten are4 washed from the from the glutenvsettlers, may be returned to the slop (hulls and fibrous part of the corn kernels) process at the steeps, while the other process 25 .by passing the material through copper reels or waters, containing much smaller quantities of over copper covered shakers; after which the soluble substances and which have been in the mixture of starch. gluten and water from the process a shorter timeare utilized as wash last-mentioned operation is passed through ne waters in the wet starch system, that is, in the silk covered sieves to remove residual slop partigerm, coarse slop and tlne slop separating oper- 3o cles therein, which latter are then subjected to ations; and that in the third place, the s'oluble a washing operation in a series of` silk covered substances,- ryellow colored substances and other reels or on silk covered shakers, forthe purpose impurities, are to a considerable extent kept out of' washing out of the ne slop the starch and of the process waters intended to be reused in the gluten which it contains. The mill starch wet starch system and are concentrated in the 35 streams (starch, gluten and water) from the process water intended for reuse in the steeps.

germ, coarse slop and fine slop separating or The relatively highly infected gluten settler water washing operations are then lrun together and with itsV larger content otr impurities and yellow tabled, according to customary practice, for the colored substances may be used for steeping with- 40 purpose of separating the gluten from the starch. out bringing'about any infection or contamina- 40 lThe starch removed from the tables', usually by tion of the material treated, because of the high flushing, is dewateredvand washed with fresh temperatures and sulphur dioxide concentrawater in lters of the displacement type operated tions used in steeping and because the material by pressure or vacuum. The gluten is allowed to treated in the steeps is in the form of unbroken 5 settle in the gluten settlers. The starch filtrate grain. In thegerm, coarse slop and ilne slop 45 and wash water, and the gluten settler water are separating operations the temperatures and sulreturned to .the process for re-use. phur dioxide concentrations are lower than in the This application is a. division of copending apsteeps and the material treated is in a nely plicatlon Serial No. 675,412 filed June 12, 1933, divided state so that it is particularly susceptible in which are disclosed several alternative metlito the action of micro-organisms and to the con- 50 ods whereby the operation of separating the taminating effect of solubles', yellowl colored subgluten from the starch is accomplished in a stances and other impurities. By using for the particularly advantageous manner by means of germ, coarse slop and iine slop separating operacentrifugal machines instead of by a tabling options a Water less infected and. containing a smaller quantity of soluble and colored substances 5B thanfthe gluten settler water, using such water to the exclusion of gluten settler water, not only is the washing of the starch on the starch filters facilitated, but a purer starch is obtained since, because of the colloidal character lof the, impurities resulting from the use of the gluten settler water in the germ, coarse slop and ilne slop separations, it is impossible to remove such impurities from the starch even by repeated Washing.

The process also gives a whiter starch. The

solubles and other impurities include substances.

is such as to insure a particularly close separa,-

tion as between starch and gluten for a given amount of water used.

The invention is illustrated in a preferred form in the accompanying drawings, in which Fig. 1 is a flow sheet diagram of the whole process; and

Fig. 2 is a more detailed diagram illustrating the course of the liquids through the centrifugal system. v

It will be understood that Fig. 1 of the drawings, for the purpose of simplification, shows single units where in practice there will be bat'- teries, for example of steep tanks, sieves, etc. The showing of machinery is purely diagrammatic. Any suitable apparatus may be used for carrying out the process steps illustrated.

The numerals on the drawings followed by the abbreviation Gal. indicate quantities of water present measured in gallons per bushel of corn ground. II'hese figures are to be taken as illustrating a practical water balance. They may vary considerably for different installations. The aim is to re-use in the system all process waters except the steep water, evaporated for the purpose of saving solubles, and the relatively small quantities of water that go out of the system absorbed in the discharged solids. However, it would be possible, obviously, to obtain some of the advantages of the invention by arrangements that might involve discharge of small quantities of the process water to the sewer; although such practice would have the disadvantages oi'. loss of some solubles and the possibility oi' stream pollution. Similarly it would be possible, but certainly not desirable, to return small quantities of gluten settler water to the wet starch system, that is the germ, coarse slop, and fine slop separations; and this might be desirable in some cases in order to bring about a proper water balance. However, the re-use of small amounts of'gluten settler water, or other highly infected water, in the wet starch system is not recommended, nor is it necessary.

Referring first to Fig. 1: A designates the steeping system; B the mill for cracking the corn to release the germs; C the germ separator in which the germs are floated off and separated from the rest of the corn; D the apparatus for washing the germs; E a coarse sieve which receives the degerminated corn from the separator C; F ane sieve for separating a starch, gluten and water mixture (mill starch) from the degerminated corn; G the mill for grinding the v washing apparatus for removing starch and gluten from the tailings from the drain sieve J;

L a concentrator for extracting water from the mill starch, from the coarse wash H and ne wash K; N, O and P, three centrifugals arranged on a modified countercurrent principle through which the combin'ed mill starch streams from the germ system, through fine sieve F, from the coarse wash H, through sieve J, and from ne wash K after concentration are passed for the primary purpose of separating the gluten from the starch and also for the purpose of concentrating solubles in the gluten overow. A larger or smaller number of centrifugals might be employed. Q is a dewatering and washing filter which receives the starch from the last centrifugal P of the series. 'I'he starch is washed in filter Q with fresh water by which is intended either tap water or other water containing a small quantity of solubles or other impurities. R is a settler or other dewatering means, for removing water from the gluten in the overow from the centrifugal system; and S is a press for pressing the gluten from the settler R to extract more water therefrom.

The conduits between the above enumerated instrumentalities (which conduits will be referred to as pipes, although they may in some cases be troughs, conveyors or other conducting means) will be referred to in connection with the description of the operation of the system which is' as follows:V

- Operation of procesa-The corn containing 1.3 gallons of water enters the steeping system A at Ill. From the steeping system 8.0 gallons of steep water are withdrawn through pipe I I to the evaporator (not shown), where this water is evaporated to a sumcient extent, for example, to mix with the slops and gluten for the manufacture' of cattle feed. In this or other suitable ways the corn solubles leeched out of the corn in the steeping operation, lare saved, together with those contained in the process water used for steeping the corn.

The steeped corn with 5.0 gallons of water passes through pipe I2 to the mill B where it is coarsely ground. The ground material passes through pipe I3 to the germ separator C :from which the germs are floated ofi, passing through pipe Il to the germ washing system D. Starch milk passes from the germ wash D through pipe i5 back to the separator C for supplying liquid of the necessary gravity for effecting the sepaf ration as between the germs and the rest of the corn. The washed germs are discharged from the germ-washing system at i6 with 0.5 gallon of water. The degermlnated corn is discharged from the separator C through pipe I1 to coarse sieve E. The tailings or slop from the coarse sieve E pass through pipe I8 to mill G. 'Ihe starch milk from sieve E passes through pipe il to the' fine sieve F, the tailings or slop from which pass through pipe 20 to the mill G the material entering the mill containing 1.2 gallons of water. The mill starch passing through the fine sieve F goes into a pipe a: leading to the centrifugal machines. This stream contains 8.0 gallons of water, together with starch, gluten, solubles and suspension colloid substances and is practically free of all bran and fiber.

The grits and slop entering mill G are there ground as finely as possible, and the ground material passes through pipe 2l to the coarse slop wash H consisting of a series of copper reels or shakers, ordinarily, through which the material is passed successively. 'Ihe coarse slop, containing 0.4 gallon of water, passes out of the system at 22. The bulk of the water, (12.6 gallons) containing starch and gluten, and some ne bran particles, passes from the coarse slop wash H through pipe 23 to-the drain sieve J and thence into mill starch pipe y. The tailings from the sieve J, containing 5.6 `gallons of water pass through pipeZ tothe ne slop wash K which consists, ordinarily, of reels or shakers covered with bolting cloth. The fine slop containing 0.3 gallon of water is discharged from the system at 25. The mill starch from the ne slop passes into ripe 2 L is a concentrator, which may be a settling tank but is preferably a vacuum lter, which receives 14.4 gallons of mill starch from the fine wash K'through pipe z, v4.0 gallons of mill starch from the coarse wash H through the drain reel J and branch 26 of pipe y, and 0.6 gallon of the overow from the second centrifugal machine O through pipe 21, the latter as a Water balancing expedient. These liquids are concentrated in the concentrator L, by extraction of water, so that the solids from the concentrator discharged through the other branch of pipe e have a water content of 1.9 gallons. This material is mixed with 3.0 gallons of mill starch from the coarse slop Wash through pipey and 8.0 gallons from theV germ system through pipe :c making. 12.9 gallons going to the centrifugal N. through the line marked :Breathe density of which is approximately 13.5 Baume. The underflow from the first centrifugal N, 9.5 gallons, and consisting largely of starch,

passes through pipe 23 to the second centrifugal O. The underflow from centrifugal O, 9.0 gallons, passes throughpipe 29 to centrifugal P. The underflow from centrifugal P, 8.5 gallons,

passes through pipe 30 to the'washing lter Q.

It will have a density of about 16.5 Baume; the now of liquids through the centrifugal system being controlled so as to increase the density of the discharged starch liquor to a density proper for filtering. The starch from centrifugal l? is first dewa'teredin the filter Q and is then washed with fresh water, 3.1 gallons, introduced through pipes 31, 32. The purified starch containing 3.1 gallons of water is discharged from the system at 33. The total fresh water introduced into the system is 11.7 gallons. 8.6 gallons of this pass through pipe 3i Vto the third centrifugal P. 9.1 gallons of the overflow from the third centrifugal i pass through pipe 33 to the second centrifugal O, 2.4 gallons, however, passing back through pipe 34 tothe third centrifugal P. Of the overow from the second centrifugal O, 0.6 gallon, as stated above, pass through pipe 21 to the 'concentrator L, while 1.9 gallons pass through branch pipe 3E back tothe second centrifugal O and 9.0 gallons go forward to the first centrifugal N throughpipe 36.' lrifhe overflow from centrifugal N (112.4 gallons) passes intopipe 3i.

By 'diverting a part of the overflow from each centrifugal (except the first) and" sending such is increased with, consequently, a repeated separation of starch from gluten.

As described in application Serial No. 675,412, the centrifuging operation involves introducing the fresh water, or, as the case may be theoverflow from one centrifugal to the next, into the underow zone of the centrifugal to which the liquid passes in each case, with the result that the solubles and other impurities are concentrated in the overflow from the 'rst centrifugal. Inasmuch as the overflow yfrom the rst centrifugal is sent back to the steeps, after the gluten has been removed therefrom, the advantage in concentrat- "ing the solubles and other impurities in this water will be obvious. This concentration is due in part to dilution but also, apparently, to displacement since there has been found to be agreater concentration of solubles in the overflow than can be accounted for, mathematically, on the basis of dilution alone. That is the starch milk before it reacties the underflow zone has split off from it water with a high solubles content which is reaplacedby the wash water having a relatively lower solubles content.

'I'his method of centrifuging is illustrated in the detailed diagram of the centrifugal system xshown in Fig. 2 of the drawings. In this diagram a indicates the starch underow zone of the centrifugal machine, in each case, and b the outlet for gluten which leads from the overflow zone Vof the machine; c designating the rotating shell of the machine, which may be of any preferred construction. The fresh water pipe 3| and the overflow pipes 33 and 36 deliver their liquids to the starch zone a of the centrifugal machine so as to bring about the displacement effect above described and ultimately the concentration of the -major portion of the solubles of the mill starch in the streams of gluten and water discharged from the centrifugal system.

The process waters are returned to the process as follows: The overow from the first centrifugal, 12.4 gallons, passes through pipe 31 to the settler R. The water from the settler passes through pipe 38 to the steeps A. The gluten from the settler passes through pipe 39 to the press S, they water from the press going to pipe 38 and the steeps through pipe 40. 11.7 gallons of Water enter the steeps giving a draw-on at Il of 8.0 gallons. 'I'his rather large draw-off is due to the comparatively large quantity of fresh water used in filter and` centrifugais. The gluten is discharged from `press S at Il with 0.7 gallon of water.

The water from the concentrator L passes through pipe t2, 8.5 gallons going to the germ wash D and 8.0 gallons, through branch pipe 43, to the coarse wash H land v0.6 gallon, through pipe M to pipe 45 which conducts the starch wash Water from filter Q, 8.5 gallons, to the fine wash K.

'I'he water from the concentrator L contains a relatively small amount of soluble substances because of the lowI solubles `content of the mill starch from the coarse and iine washes in comparison with the mill starch from the germ system.. It is for this reason that in concentrating the mill starch before centrifuglng it, it' is prferable to so treat all of the fine wash milll starch and as much of the coarse wash mill starch asnecessary in order to obtain-the required high density in the liquid treated in the centrifugal machine.

By the above arrangements the greater the solubles content of a process water the closer the water will be returned to the pointcf ultimate discharge from the system, the steeplng process, thus keeping the later stages of the process as 44 are small, it may be said that substantially all of the` gluten overflow from the centrifugal system goes to the gluten settler and thence to the steeping system; substantially all of the water obtained by dewater'ing the starch from the centrifugal system, centrifugal machine P, goes to the ne wash; and substantially all of the wa ter derived from the concentrator L is distributed as between the germ wash and coarse slop wash.

.The concentration of the mill starch at L, which raises the density ofthe combined mill starch streams entering the centrifugal system, is an important feature of the process. Centrifugal machinery is relatively expensive and costly to operate and the concentration of the mill starch ,results in a proportionate decrease in required centrifugal equipment. What is perhaps more important, it is more feasible to centrifuge a. liquor of relatively high density than a liquor of the density of the mill starch as it comes from the separating operation. The denser liquor can be held in the centrifugal machine in order to allow time for separation without making the starch discharge orifices so small that they are likely to be clogged.

No claim is made to any invention common to this application and the other forms disclosed in the parent case Serial No. 675,412 of which the present case is a division, the ygeneric claims being included in the parent case and certain other forms being claimed specifically in other divisional applications of said parent case. It is the intention, however, to cover herein all applications of the described process to other industries than starch making together with all modifications of the particular form of the invention disclosed herein within the scope of the appended discharged solids, are re-used in the process comprising: steeping and comminuting the com; subjecting the comminuted corn to separating operations in water; concentrating the mill starch by extracting water therefrom Aand returning said water to the separating operations; subjecting the concentrated mill starch to a series of centrifuging operations, against a wash liquid introduced into the last centrifugal, in which a part of the overflow from each centrifugal, except the i'lrst, goes to the next centrifugal in advance and the rest of the overflow is returned to the centrifugal from which it came; and reusing the water of the overflow from the first centrifuging operation for steeping corn.'

' 3. The process of manufacturing starch from corn in which substantially all process waters, except the steep water and water absorbed in the discharged solids, are reused in the process comprising: .steeping and comminuting the corn;

' subjecting the comminutedA corn, to separating operations in water; subjecting the milly starch to from solubles as possible. Since the quan- 'tities of liquid which pass through pipes 2l' and a series of centrifuglng operations against a wash liquid introduced into the underflow zone of the last centrifugal in which a part ofthe Voverflow from each centrifugal, except the first,

is introduced into the next centrifugal in advance, in the underflow zone thereof, and the rest returned to the centrifugal from which it the overow to be returned to the centrifugal from which it came.

5. Method of separating materials which conn sists in causing a water suspension of the materials to be passed through a series of centrifugals against a wash water introduced into the underow zone of the last centrifugal; and causing a portion of the overflow from one centrifugal to be introduced into the underflow zone of a centrifugal in advance in the series, and the rest of the overflow to bereturned to the underflow zone of the centrifugal from which it came.

6. Method of separating materials which consists in causing a water suspension of the materlals to be passed through a series of centrifugals against a wash liquid introduced into the last centrifugals; andin the case of some of said operations causing a portion of the overflow from the centrifugal to be introduced in the next centrifugal in advance and the rest of the overflow to be returned to the centrifugal from whichy it came.

'7. Method of separating materials which consists in causing a water suspension of the materials to be passed through a series of centrifugals against a wash water introduced into the underiiow zones of said centrifugals consisting of fresh water in the case of the last centrifugal and, in the case of the others, overflow from a later centrifugal of the series; and, in the case of some of said operations, causing a portion of the overflow from the centrifugal to be returned to the centrifugal from which it came.`

8. Process of manufacturing starch from corn which comprises: subjecting the mill starch to a. series of centrifuging operations through which the underflow moves in one direction and the overiiow in the other, introducing the overflow into the underow zone of the centrifugal operation which said overiiow enters; and, in the case of some of said operations, diverting a part of the overflow back to the centrifugal operation from which it came.

9. Process of manufacturing starch from corn which comprises: steeping and comminutlng the corn; subjecting the comminuted corn in water to separating operations which yield mill starch streams of higher and lower soluble contents; concentrating mill starch of lower solubles content; mixing the concentrating mill starch with the rest of the mill starch and subjecting the mixture to a series of centrifuging operations in which theunderflow moves in one direction and the overiiow in the other; diverting, in the case of some of said centrifuging operations a part of the overow back to the centrifugal operation fromwhich it came; removing the gluten from the overflow from the centrifuging operation by settlingand re-using concentrating mill starch of' lower solubles content; mixing the concentrated mill starch with the rest of the mill starch and subjecting the mixture to a series of centrifuging operations in which the underflow moves in one direction and the overflow in the other; diverting, in the case of some of said centrifugal operations, a part of the overow back to the centrifugal operation i from which it came; removing the gluten from the overow from the centrifugal operation by settling and re-using the water in the steeping operation; dewatering the underflow from the centrifuging operation; and using the waters derived from said concentrating and starch dewatering operation in the steps of the process subsequent to steeping at points nearer the steeping end of the system in proportion to the solubles contents of said'waters respectively.

11. Process of manufacturing starch from corn which comprises: steeping the cor'n; subjecting the steeped corn, in a comminuted state, to germ, coarse slop .and fine slop separations; extracting water from the mill starch from the fine slop separation and returning substantially all of this water to the germ and coarse slop separation; subjecting the concentrated mill starch from the ne slop separation with the mill starch from the germ and coarse slo'p separations to a series of centrifuging operations in some of which operations a portion of the overow is returned to the centrifugal from which it came; returning sub- Jstantially all of the over'ow from the ilrst centrifuging operation, after removal of gluten from said overflow to the steeping operation; dewatering the starch from -said centrifugal operations; and re-using substantially all of the water from the de-watering operation in the ne slop separation.

12. Method of separating starch from gluten which comprises subjecting a water mixture of the starch and gluten to a series of centrifuging operations in which the underilow, carrying the starch, moves successively from operation to opf eration, and a portion of theoverfiow, carrying the gluten, moves, in the opposite direction, from a operation to operation, while a portion of the overow from each operation is returned to the operation from which it came.

13. Method of effecting separation by centrifugal force which yconsists in causingthe liquid mixturel of the materials to be passed successively through a plurality of entrifugals and causing a wash liquor to pass through said centrifugals inthe opposite direction; the wash liquid and the overflow from one centrifugal to the next entering the under'ow zone of the centrifugal, a portion of the overow in eaclL case being returned to the centrifugal from which it came.

14. Centrifugal apparatus comprising a plurality of centrifugals; means for introducing the underflow from each centrifuge (except the last) into the next machine; means for introducing a Wash water into the' rst centrifuge; means for introducing a wash water into the last centrifuge;

means for discharging the overflows from the' first andsecond centrifuges; means for introducing overflow from the last centrifuge into the next machine in advance, and means for diverting some of the overflow from each centrifuge, except the first, back into the machine from which it came. Y

15. Centrifugal system comprising a series of centrifugal machines; means for introducing a liquid containing the substances to be 'separated' into vthe first centrifugal; means for introducing the underow l from each centrifugal into the next centrifugal of the series; means for introducing a wash water into the last centrifugal of the series; means for discharging out of the system the overflow from the rst centrifugal; means for discharging out of the system part of the overflow of the second centrifugal; and means for diverting part of the overow from each centrifugal,` except the first, back to the centrifugal from which it came.

ALFRED H. KELLING. 

